Free Learning Forever Initiative by Packt Publishing
Packt Publishing has started a new initiative; offering a different ebook for free every day. To get it, you need to have a free account on their web site, so that it can be added to your collection. You also only have a 24 hour window during which the daily book is available, before it is replaced with the next one. Though, once it is added to your collection, you can always download it again in the future.
As you can see from the initiative web page, the books they are offering for free cover a really wide spectrum of topics, so everyone should be able to find something for his taste; e.g. yesterday's book s was the first edition of Learning NServiceBus, the successor of which I have recently reviewed.
There have already been similar promotions in the past, but they have all been of shorter period. The current set of 24 books on the page is the second one in a row, and there's still 9 days till the end. It's also quite possible, it will continue with another set afterwards, although this doesn't seem to be communicated anywhere on the page. Even if not, you should check the page every day until then and download any books that might interest you.